- Volume 56, Issue 2, 1969
Volume 56, Issue 2, 1969
- Article
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The Fine Structure of the Zoospores and Cysts of Allomyces macrogynus
More LessSUMMARYZoospores and cysts of Allomyces macrogynus have been studied by electron microscopy. A membrane-bound nuclear cap filled with ribosomes surrounded a single nucleus. Mitochondria and lipid bodies were found at the periphery of the nuclear cap. The flagellum was attached close to the nucleus by two tubular structures running anteriorly along both sides of the nuclear cap. During encystment the axoneme was retracted, the nuclear cap dissected with endoplasmic reticulum and the mitochondria increased in number and started to elongate. Concentric granules and/or mitochondria were found embedded in the nuclear cap.
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Deoxyribonucleic Acid Base Compositions of Mycoplasma Strains of Avian Origin
More LessSUMMARYThe guanine + cytosine (GC) base compositions of deoxyribonucleic acids (DNA) of avian mycoplasmas, as well as strains from other sources, were determined from buoyant density in CsCl. The values from our work ranged from 24·0 to 35·7 moles%. There were small clusters at about 35% and 32% but the rest of the values ranged continuously from 24·0% to 30·5%. From reports in the literature, the values for the Mycoplasma group ranged from 22·8 to 41·0.
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The Separation of Neuraminidase Activity from other Pathological Activities of a Culture Filtrate of Clostridium sordellii cn 3903
More LessSUMMARYThe neuraminidase activity of a culture filtrate of Clostridium sordellii cn 3903 was separated on a Sephadex column from the oedema-producing, haemorrhage-producing and lecithinase activities. It is concluded that the neuraminidase of C. sordellii is not able by itself to produce oedema and haemorrhage.
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Toxicity of Hyperbaric Oxygen to Yeasts Displaying Periodic Enzyme Synthesis
More LessSUMMARYExponential cultures of Saccharomyces cerevisiae and Candida utilis exposed to oxygen at ten atmospheres did not undergo any further cell division during treatment. All cells ultimately died when the treatment was prolonged for several days. Populations survived considerably longer with ethanol as a carbon source than with glucose. Stationary-phase populations were more resistant than exponentially-growing populations. The cell cycle of S. cerevisiae shows two points of resistance to oxygen toxicity which corresponded to two periods of catalase synthesis in air. These results are attributed to periodic synthesis of protective enzymes.
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Degradation of Ursolic Acid, a Major Component of Apple Wax, by a Pseudomonad Isolated from Soil
More LessSUMMARYA Pseudomonas sp. isolated from orchard soil utilized ursolic acid (C30H48O3), a major component of apple wax, as a sole source of carbon. It evolved 14CO2 from [14C]ursolic acid and incorporated the label into all usual cell constituents; it formed a labelled polar metabolite of ursolic acid. Orchard soil thus contains at least one organism which is able to degrade the terpenes of the cuticular wax of plants.
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Immunochemical Analysis of Streptococcus bovis, Strain s19, Cell Walls
More LessSUMMARYTwo antigens, a glucose-rich capsular polymer and a cell wall carbohydrate consisting of N-acetylglucosamine, glucose and rhamnose, were isolated from Streptococcus bovis, strain s 19. N-acetylglucosamine and a haptenic fraction rich in glucosamine inhibited approximately 56 and 63% of the quantitative precipitin reaction between the s 19 cell wall carbohydrate and its homologous antiserum, respectively. A cross-reactivity between a preparation of azo-protein, which consisted of terminal β-N-acetylglucosaminide residues, and s 19 antiserum substantiated the fact that N-acetylglycosamine is one of the major antigenic determinants of the s 19 cell-wall carbohydrate.
Haptenic inhibition studies have not revealed any structural feature of the antigenic determinant of the glucose-rich capsular polymer.
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Behaviour of Streptomycetes in Soil
More LessSUMMARYMost of the conidia from eight different streptomycetes did not germinate in natural soil under conditions apparently suitable for their germination. When germinated in nutrient solution and then added to soil, they grew for a limited period, sporulated and then the vegetative hyphae disappeared, leaving behind only spores.
Streptomycete conidia produced naturally in garden soil decreased in number by about a half after 12 days. Nevertheless, the conidia are the main means of survival and it appears that streptomycetes exist in soil mainly as spores. Mycelia also existed, but in the main were restricted to micro-sites where nutrient was available.
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Sporulation in Bacillus subtilis. Establishment of a Time Scale for the Morphological Events
More LessSUMMARYChemostat cultures of Bacillus subtilis can be obtained in which a large proportion of the cells are initiated to sporulation. In a steady-state culture the fraction of cells which exhibit any particular stage of spore development is a function of the time taken for a cell to reach that stage after having been initiated to spore formation, and of the time required for the cell to pass through that stage. Equations describing this relationship have been derived. From these equations and from values for the fractions of cells exhibiting the morphological stages of spore development seen in electron micrographs, a time scale for the morphological events occurring during sporulation has been constructed.
By observing the effect of a sudden decrease in flow rate of a continuous flow system initially at steady state it was possible to time the occurrence of specific events, biochemical or physical, which were connected with the formation of spores. By this means, refractility was shown to be associated with stage V.
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Nitrogen Fixation by Cultures and Cell-free Extracts of Mycobacterium flavum 301
More LessSUMMARYGrowth, nitrogen fixation and acetylene reduction by Mycobacterium flavum 301 (ncib 10,071) were increased with sodium lactate, pyruvate, gluconate or succinate as compared with ethanol, a recommended substrate. Yeast extract could be replaced with (NH4)2SO4; in continuous culture a source of fixed nitrogen could be omitted altogether. Growth, nitrogen fixation and acetylene reduction all increased at lowered pO2 values. Wholly anaerobic conditions did not support growth. Nitrogen fixation was confirmed isotopically.
Cell-free extracts performed the following reductions: N2 to NH3, H+ to H2, C2H2 to C2H4, KCN to CH4, CH3NC to CH4 + C2H4 + C2H6. An ATP-generating system, Mg2+, Na2S2O4, and anaerobic conditions during preparation and assay of extracts were required. 3·5 mole ATP were hydrolysed to release 1 mole H2. Pyruvate, α-ketobutyrate, α-ketoglutarate, succinate, glucose and glucose-6-phosphate did not replace dithionite. ADP, AMP or high concentrations of ATP inhibited reduction. Activity was associated with a particle which sedimented at 145,000 g over 3·1/2 hr. The nitrogenase system of M. flavum thus resembles the particulate system of Azotobacter, rather than the soluble pyruvate-utilizing system of Clostridium pasteurianum.
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Numerical Taxonomy of Some Named Coryneform Bacteria
More LessSUMMARYNumerical analysis of data for seventy coryneform bacteria bearing the following generic names, Mycobacterium, Nocardia, Jensenia, Listeria, Erysipelothrix, Kurthia, Brevibacterium, Arthrobacter, Cellulomonas, Microbacterium and Corynebacterium, was done by using 70 coded features and both single and complete linkage clustering programs.
Three major phenons were detected, probably corresponding taxonomically to the present family level in the taxonomic hierarchy. The first included Listeria, Kurthia, Erysipelothrix, certain Microbacterium strains and Corynebacterium species of animal origin. The second included rapid-growing Mycobacterium species, Nocardia and Jensenia. The third was a more illdefined group of Arthrobacter, Brevibacterium, Cellulomonas, Microbacterium and certain other species. We suggest that all three phenons belong in the order Eubacteriales under the possible family names of Corynebacteriaceae, Mycobacteriaceae and Arthrobacteriaceae respectively.
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Carboxymethylcellulase Production by Verticillium albo-atrum
More LessSUMMARYA strain of Verticillium albo-atrum produced CM cellulase in liquid culture containing either cellulose powder or carboxymethyl-cellulose (CM cellulose) as sole carbon source, and when the fungus was growing in its natural host (lucerne). The CM cellulase liberated when the fungus was grown in liquid culture was fractionated on Sephadex G75, giving three major peaks and two minor peaks of cellulase activity. The materials of the three major peaks differed from each other in molecular weight, Michaelis constant and pH/activity curve, but were the same whether induced by cellulose powder or CM cellulose. Incubation of the materials of the three major peaks with CM cellulose resulted in the production of only medium-length polymers and cellobiose. No cellobiase was detected in liquid culture. CM cellulase activity was found to be only slight in the living infected lucerne tissue but was considerable in the dead infected tissue.
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Polarity of Flagellar Growth in Salmonella
More LessSUMMARYThe phenomenon whereby Salmonella cells produce curly flagella in media containing p-fluorophenylalanine was used to investigate the polarity of flagellar growth. Salmonella typhimurium lt2 in logarithmic growth in broth was transferred to minimal medium or saline, or their flagella shortened by mechanical breaking. Then, after 2 to 3 hr at 37° in a medium containing p-fluorophenylalanine the distributions of number, length and shape of their flagella were observed. Curly waves appeared at the distal portions of flagella. The growth rate of a flagellum decreased as its length increased, reaching zero at approximately five normal wave-numbers (about 15 μ). The growth rate of flagella shortened by mechanical breaking was not less than that of intact ones of similar length. The decline is attributed to decrease in transport efficiency with increase in length rather than to ageing of the flagellum-forming apparatus.
A normal flagellar strain and a curly mutant strain of Salmonella abortusequi were grown together in broth. Numbers of both types of rods and flagella increased to 1·5-fold in 3 hr. At this stage, neither heteromorphous rods nor single flagella having both normal and curly waves were detected. Hence, flagellin molecules reach the top of a growing flagellum without being excreted into the culture medium.
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Factors Affecting the Toxicity of Oxygen Towards Airborne Coliform Bacteria
More LessSUMMARYThe maximum bactericidal effect of oxygen on airborne coliform bacteria occurred at the lowest relative humidity tested. Escherichia coli commune and Klebsiella aerogenes were very much less sensitive than E. coli b and E. coli jepp.Only a small partial pressure of oxygen in a nitrogen-oxygen mixture at atmospheric pressure was required to produce the maximum effect. The oxygen toxicity for each bacterial strain was altered by changing the growth conditions or by including certain chemicals in the spray fluid. These chemicals are protective to freeze-dried bacteria and therefore inactivation of oxidative enzymes in freeze dried and airborne bacteria probably occur by similar mechanisms. The same oxidative enzymes in bacterial colonies were slightly inactivated by hyperbaric oxygen pressures.
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Phage-induced Alteration of Enzymic Activity in Lysogenic Mycobacterium smegmatis Strains
More LessSUMMARYChanges in the amidase, nitrate reductase and phenolphthalein sulphatase activity of Mycobacterium smegmatis were observed following B1-lysogeny. These changes were more consistent in lysogenic derivatives of strains sn2 and sn14 than in those of strain sn10. Strains sn2 and sn14 appeared to differ from sn 10 only in that the former possessed a functional salicylamidase locus while the latter did not. Emergence of various phenotypes in the same strain and during the same lysogenic event were observed. Multiple sites of phage integration may have accounted for the variation of sn10 (B1) phenotypes.
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Properties of Proteus mirabilis and Providence Spheroplasts
More LessSUMMARYProteus mirabilis strain 13 and Providence strain nctc9211 were converted to osmotically sensitive spheroplasts by growth in the presence of penicillin or glycine in sucrose-supplemented or unsupplemented medium. Lysozyme in the presence of tris and ethylenediaminetetra-acetic acid (EDTA) converted both these strains to spheroplasts. Penicillin spheroplasts could be stabilized with sucrose, streptomycin, spermine or di-valent cations. Electron micrographs of these spheroplasts demonstrated that the outer layer of the bacterial cell wall was retained. Penicillin-induced spheroplasts possessed receptor sites for bacteriophages.
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